The present invention relates to an electronic musical instrument, and more particularly, to an electronic musical instrument wherein tones are produced through digital processings.
In recent years, the technology of integrated circuits has undergone a remarkable progress, resulting in the development of various digital technics for generating musical tones. For one example, there is disclosed in the prior art an electronic musical instrument, in which a waveshape is stored in digital representations and is repetitively read out at a selectable rate, therefrom producing a musical note.
But this method for producing a musical note has disadvantages in that the quality of the produced musical tone is fixed by the waveshape which is previously stored, and that, for different tone qualities, different memories must be provided for storing different waveshapes. And, moreover, this method for producing a musical note is not suitable to change the generated tone quality as a function of time.
For another example, there is known in the prior art a musical instrument wherein a desired waveshape is synthesized by adding the fundamental frequency component and the harmonic components. But this method of synthesizing a tone waveshape has a disadvantage in that a large number of harmonic components must be processed when a precise amplitude control is required up to a higher degree of harmonics to obtain a high grade control for the tone quality. When many harmonic components are processed in a time division system, the system clock frequency must be increased in proportion to the number of the harmonic components, and when parallel processings are introduced to lower the clock frequency, parallel processing circuits must be provided resulting in the increase of the structure of the equipment.